InnoDB 1.1.2 was released with MySQL 5.5.6-rc

interface related change, will put back in once gain approval.

It was needed when InnoDB Plugin was distributed independently of MySQL.
Approved by Vasil Dimov.

In early development of delete buffering, we did allow B-tree pages
to become empty as a result of buffered deletes. That caused fundamental
problems. The fix was to refuse buffering purge operations unless
the page can be guaranteed to be nonempty. Remove an attempt to
cope with empty pages when merging inserts.

This was replaced with REC_OLD_INFO_BITS in MySQL 5.0.3.

Remove non applicable licensing files

storage/innobase/COPYING is in the MySQL top level directory and
storage/innobase/COPYING.Sun_Microsystems is not applicable anymore
now that Oracle and Sun are one company.

On Solaris with version 3.4.6, the ha_example.so shared library is built
with DTrace and the server is built without DTrace support. This occurs
because dtrace.cmake disables DTrace support for 3.4.6, but still set
HAVE_DTRACE, which causes probes_mysql.h to include probes_mysql_dtrace.h
instead of probes_mysql_nodtrace.h.

This patch fixes this by not setting HAVE_DTRACE on Solaris for GCC 3.4.6.

 create data dir correctly in initial_database target on Windows
 handle case where INSTALL_MYSQLTESTDIR is empty (e.g someone does not want
 to install tests)

          thread-specific variables weren't set when we load error message files.

per-file comments:
  libmysqld/lib_sql.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
      we need to call my_thread_init() once more. Normally it's called at the my_init()
      stage but that doesn't happen on the second my_init() call.

  sql/derror.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
     use default errors for the embedded server.

  sql/mysqld.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
        unregister server errors in clean_up(). Without it the error list contains
        that on the second mysql_server_init() which is not good.

  sql/set_var.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
        sys_var::cleanup() call instead of the destructor

  sql/set_var.h
Bug#53251      mysql_library_init fails on second execution with embedded library
        sys_var::cleanup() introduced instead of the destructor
        
  sql/sys_vars.h
Bug#53251      mysql_library_init fails on second execution with embedded library
        Sys_var_charptr::cleanup() implemented

Merge cleanup, fixed a build warning:

my_getopt.c:156: warning: 'opt_found' may be used uninitialized in this function

        When in embedded-serve mode, mysqltest tried to run '--send' commands in the separate thread.
        That upsets some engines (InnoDB particularly) as the transaction has to be executed in the same
        thread completely. So i implemented some different approach. So we create one separate thread for
        each connection and execute all the queries of this connection inside it. Looks even simpler than it was
        for me.

per-file comments:
  client/mysqltest.cc
Bug#54861      Additional connections not handled properly in mtr --embedded
        Now the connection has one running connection_thread() attached. And sends all the
        query and read-result requests to it.